In the mixing of large bodies of liquid, several different types of mixers have been used, such as water floats and pumps. Generally, the flotation type does not sufficiently mix the water in a large sewage lagoon to provide aerated flow throughout the entire impoundment. Certain mixers are commonly used in aerating lagoons in which active biological solids are in equilibrium with an applied waste. The basin is of sufficient depth, normally six to twelve feet and oxygen is furnished by mechanical aeration to create a turbulence level sufficient to provide adequate liquid mixing. As a result of the mixing, uniform distribution of the waste and dispersion of the oxygen is achieved and rapid and efficient waste biodegradation occurs.
Some aerators, such as our horizontal mixing aerator disclosed in U.S. Pat. No. 4,431,597 are sufficiently controllable in various directions of flow for maximum efficiency. Our previous aerator injected pressurized air into the body of liquid by providing an air flow line or conduit in the form of a flexible hose, which was draped over the sidewall of the sewage lagoon, extended down into the body of liquid and connected to an air injection nozzle affixed to one of the support brackets holding a submersible motor and propeller arrangement. This hose was excessively heavy to lift, even by a winch, and foreign matter tended to collect on the rough surface of the hose so that it was an extremely filthy job to retrieve the hose when the mixer was lifted for inspection. Moreover, the material of the hose, such as neoprene rubber after a period of time became subject to attack by bacterial organisms and became sticky, slimy and increasingly subject to cuts and leaks.